The present invention relates to a lathe steady rest. More particularly this invention concerns such a rest used to radially support a workpiece rotating about a center in a lathe and subject to chip-removing machining at a location between the steady rest and the lathe headstock or tailstock.
A standard steady rest for a lathe has a frame adjacent the axis about which a lathe rotates a workpiece, a pair of arms pivotal on the frame about arm axes parallel to the workpiece axis and having outer ends radially displaceable relative to the workpiece axis, and a slide displaceable radially of the workpiece axis on the frame and having an outer end turned toward the workpiece. These outer ends are angularly spaced about the axis. Respective rollers are rotatable on the outer ends about roller axes parallel to the workpiece axis and can radially engage the workpiece. Respective caps mounted on the arm outer ends over the respective rollers have scraper blades and serve to prevent particles, such as grit or turnings produced by the adjacent machining operation, from getting between the rollers and the workpiece. The machining operation normally generates considerable such particles and, if they get into the steady, they can move the workpiece off center.
With time some of the smaller particles get under the roller covers and between the rollers and the workpiece. They become flattened there, either on the roller or on the workpiece, and create an out-of-round condition. The steady rest must therefore be meticulously cleaned between machining cycles and, sometimes, the machining operation must be halted so it can be cleaned.
It is therefore an object of the present invention to provide an improved lathe steady rest.
Another object is the provision of such an improved lathe steady rest which overcomes the above-given disadvantages, that is which effectively prevents particles from becoming lodged between the rest and the workpiece.
A lathe steady rest has according to the invention a frame adjacent an axis about which a lathe rotates a workpiece, a pair of arms pivotal on the frame about arm axes parallel to the workpiece axis and having outer ends radially displaceable relative to the workpiece axis, and a slide displaceable radially of the workpiece axis on the frame and having an outer end turned toward the workpiece. The outer ends are angularly spaced about the axis. Respective rollers rotatable on the outer ends about roller axes parallel to the workpiece axis radially engage the workpiece. Respective caps mounted on the arm outer ends over the respective rollers have passages with outer ends directed radially inward against the workpiece adjacent the respective rollers. A fluid is supplied under pressure to the passages to flush particles from the workpiece. The chamber allows the respective cap to change position without losing pressure in its passages.
Thus the fluid, which can be compressed air that also acts as a coolant, effectively cleans from the workpiece any particles that might be able to get under the roller cover. Since this flushing operation takes place under the roller cover, a separate shield for catching the particles is not needed.
The caps according to the invention are pivotal on the respective outer arm ends generally about the respective roller axes. The frame is formed with passages connected to the fluid supply and the arms are formed with chambers connected to the passages of the arms and of the frame. Thus this system can be used on workpieces of different diameter. Each cover has a respective scraper blade engageable with the workpiece and each arm is provided with a spring urging the respective scraper blade into radial engagement with the workpiece.
The passage outer ends are directed tangentially upstream from the respective rollers. This ensures the best flushing effect.
The frame is formed adjacent the slide with a pocket having a cover forming an outlet opening. The fluid-supply means are connected to the pocket for projecting the fluid from the opening. Since the axis of movement of the slide normally forms a small angle with the horizontal, two of the pockets having covers and openings angularly flank the slide. In use a plug blocks one of the openings of the pockets, typically the opening downstream of the roller. Thus only the upstream side likely to foul is cleared; the other downstream side is closed to save pressure.